Abstract
The damages of brittle materials (alumina-carbon refractories) subjected to compressive stress or thermal shock were evaluated using ultrasonic pulse-echo method. The changes of the wave propagation velocities obtained from the base-reflected echo were in good correspondence with the damage processes of the used materials under uniaxial compression test. It was found that the intensity of the peak frequency of the back-scattered waves analyzed by FFT decreased as the damage progressed. In compression test, damages occurred even in unloading process. In the specimen damaged by thermal shock, the greater the equivalent normal stress became, the greater the damage did in tensile stress region. It was found that even in compressive region, damage was observed to some extent.
